There has been a great demand for image forming apparatuses such as printers supporting A4-size printing in portrait orientation. Printers that support A4-size printing in landscape orientation (or A3-size printing in portrait orientation) have also been in great demand. Recently, printers that support printing on large-size printing paper of A2 size or larger are now in increasing demand. In order to support printing on the large-size printing paper, the printers need, as an image carrier, a photoconductive drum having a width larger than the width of the printable area of the large-size printing paper. However, such a large-size photoconductive drum is exceedingly expensive compared with an A4-size or A3-size photoconductive drum. Consequently, conventional photoconductive drums whose widths are larger than the width of the printable area of the large-size printing paper as well as conventional image forming apparatuses having such a large-size photoconductive drum to support printing on the large-size printing paper are gaining little market acceptance.